Media Uploads Hang using Chrome and HTTP/2

[pbarnhart]

Media uploads - using both the WordPress uploaded and the default browser uploader - hang when the server is using HTTP/2. Server configured with Apache/2.4.18 (Ubuntu) OpenSSL/1.0.2h - ALPN support confirmed, pagespeed disabled, all plugins turned off. Functions fine under current version of Microsoft Edge.

When HTTP/2 turned off at server - and no other settings modified - Chrome works fine for image uploaded. Fairly sure errors did not occur until Chrome disabled NPN support with Chrome 51, previously there were no issues uploading media via Chrome.

[joemcgill]

Hi @pbarnhart,

Thanks for the report and welcome to Trac. Could you provide any additional information about the kinds of error messages you are seeing, including any differences in the server responses that show up in Chrome's dev console?

[pbarnhart]

There are zero error messages in console. There are no errors in the server log. Nothing when I run a server-side debug. It simply times out. When I switch the server to HTTP 1.1 everything works on Chrome. Switch it back to HTTP/2 and Chrome 51 forward fails (other browsers do fine). And the server does respond to HTTP 1.1 requests.

With some coord I can give up access to this site and can switch server back and forth re HTTP/2 if it helps. Honestly, I hope its something stupid I did because in my day job we manage about 40+ WP sites and are ready to move to HTTP/2

Here are the header responses:

WordPress Uploader

Request URL:https://momentsfromtheheart.com/wp-admin/admin-ajax.php
Request Headers
Provisional headers are shown
Accept:application/json, text/javascript, */*; q=0.01
Content-Type:application/x-www-form-urlencoded; charset=UTF-8
Origin:https://momentsfromtheheart.com
Referer:https://momentsfromtheheart.com/wp-admin/media-new.php
User-Agent:Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.89 Safari/537.36
X-Requested-With:XMLHttpRequest
Form Data
view source
view URL encoded
interval:60
_nonce:1015d6d1a9
action:heartbeat
screen_id:media
has_focus:false

Browser Uploader

Request URL:https://momentsfromtheheart.com/wp-admin/media-new.php
Request Headers
Provisional headers are shown
Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryXyknXR3wtwM2GPgO
Origin:https://momentsfromtheheart.com
Referer:https://momentsfromtheheart.com/wp-admin/media-new.php
Upgrade-Insecure-Requests:1
User-Agent:Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.89 Safari/537.36
Request Payload
------WebKitFormBoundaryXyknXR3wtwM2GPgO
Content-Disposition: form-data; name="async-upload"; filename="Dollarphotoclub_71447704.jpg"
Content-Type: image/jpeg


------WebKitFormBoundaryXyknXR3wtwM2GPgO
Content-Disposition: form-data; name="html-upload"

Upload
------WebKitFormBoundaryXyknXR3wtwM2GPgO
Content-Disposition: form-data; name="post_id"

0
------WebKitFormBoundaryXyknXR3wtwM2GPgO
Content-Disposition: form-data; name="_wpnonce"

74962560e0
------WebKitFormBoundaryXyknXR3wtwM2GPgO
Content-Disposition: form-data; name="_wp_http_referer"

/wp-admin/media-new.php
------WebKitFormBoundaryXyknXR3wtwM2GPgO--
Name
media-new.php
media-new.php
admin-ajax.php

[johnbillion]

@pbarnhart What's the value of $_SERVER['SERVER_PROTOCOL'] on the affected site please?

[pbarnhart]

[SERVER_PROTOCOL] => HTTP/2

[jeremyfelt]

Thanks for all of the info so far @pbarnhart and thanks for making the switch to HTTP/2! :)

For a basic initial comparison, we're serving HTTP/2 at WSU to ~95% of authenticated visitors now (thanks modern browsers!) and haven't seen any trouble with uploads in Chrome. However, we're on Nginx 1.11.3 rather than Apache, so it seems like that could be the right path to start troubleshooting.

If possible, would you mind sharing your Apache configuration as an attachment (publicly) or privately? It's okay if it's sanitized, but it would be nice to try to reproduce this in a VM environment.

I poked around in the Apache ​changelogs for the 2.4.x releases since 2.4.18 and there are quite a few bug fixes for the mod_http2 module. 2.4.18 itself happened well before Chrome made the switch from NPN to ALPN and is only one release into Apache's support for HTTP/2. See also the changelogs for the ​upstream project mod_h2 that donated the module to Apache as it continues to be an active project.

I didn't look into how many of those changes Ubuntu has included in recent packaging of the 2.4.18 version, but I would try to upgrade to 2.4.23 on your server before spending much time looking at other possibilities.

[joemcgill]

Sounds like this is probably a server configuration issue. I'm going to reassign to @jeremyfelt to continue reviewing and leave it open for now.

[pbarnhart]

Replying to jeremyfelt:

Nailed! Updated server to 2.4.23 and media posts via HTTP/2 now working. Thanks and glad it was a simple fix on my end. Thanks for troubleshooting this and for the reminder I need to keep up with my Apache releases :-)